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•Novel theoretical Fe-based binaries predicted by an Adaptive Genetic Algorithm.•Computational high-throughput screening of magnetocrystalline anisotropy.•Theoretical and experimental ...data of intrinsic and extrinsic magnetic properties.•Friendly Graphical User Interface with advanced search and plotting tools.
This paper describes the open Novamag database that has been developed for the design of novel Rare-Earth free/lean permanent magnets. Its main features as software technologies, friendly graphical user interface, advanced search mode, plotting tool and available data are explained in detail. Following the philosophy and standards of Materials Genome Initiative, it contains significant results of novel magnetic phases with high magnetocrystalline anisotropy obtained by three computational high-throughput screening approaches based on a crystal structure prediction method using an Adaptive Genetic Algorithm, tetragonally distortion of cubic phases and tuning known phases by doping. Additionally, it also includes theoretical and experimental data about fundamental magnetic material properties such as magnetic moments, magnetocrystalline anisotropy energy, exchange parameters, Curie temperature, domain wall width, exchange stiffness, coercivity and maximum energy product, that can be used in the study and design of new promising high-performance Rare-Earth free/lean permanent magnets. The results therein contained might provide some insights into the ongoing debate about the theoretical performance limits beyond Rare-Earth based magnets. Finally, some general strategies are discussed to design possible experimental routes for exploring most promising theoretical novel materials found in the database.
In this work, we present the program MAELAS to calculate magnetocrystalline anisotropy energy, anisotropic magnetostrictive coefficients and magnetoelastic constants in an automated way by Density ...Functional Theory calculations. The program is based on the length optimization of the unit cell proposed by Wu and Freeman to calculate the magnetostrictive coefficients for cubic crystals. In addition to cubic crystals, this method is also implemented and generalized for other types of crystals that may be of interest in the study of magnetostrictive materials. As a benchmark, some tests are shown for well-known magnetic materials.
Program Title: MAELAS
CPC Library link to program files: https://doi.org/10.17632/gxcdg3z7t6.1
Developer’s repository link:https://github.com/pnieves2019/MAELAS
Code Ocean capsule: https://codeocean.com/capsule/0361425
Licensing provisions: BSD 3-clause
Programming language: Python3
Nature of problem: To calculate anisotropic magnetostrictive coefficients and magnetoelastic constants in an automated way based on Density Functional Theory methods.
Solution method: In the first stage, the unit cell is relaxed through a spin-polarized calculation without spin-orbit coupling. Next, after a crystal symmetry analysis, a set of deformed lattice and spin configurations are generated using the pymatgen library 1. The energy of these states is calculated by the first-principles code VASP 3, including the spin-orbit coupling. The anisotropic magnetostrictive coefficients are derived from the fitting of these energies to a quadratic polynomial 2. Finally, if the elastic tensor is provided 4, then the magnetoelastic constants are also calculated.
Additional comments including restrictions and unusual features: This version supports the following crystal systems: Cubic (point groups 432, 4̄3m, m3̄m), Hexagonal (6mm, 622, 6̄2m, 6∕mmm), Trigonal (32, 3m, 3̄m), Tetragonal (4mm, 422, 4̄2m, 4∕mmm) and Orthorhombic (222, 2mm, mmm).
References:
1 S. P. Ong, W. D. Richards, A. Jain, G. Hautier, M. Kocher, S. Cholia, D. Gunter, V. L. Chevrier, K. A. Persson, and G. Ceder, Comput. Mater. Sci. 68, 314 (2013).
2 R. Wu, A. J. Freeman, Journal of Applied Physics 79, 6209–6212 (1996).
3 G. Kresse, J. Furthmüller, Phys. Rev. B 54 (1996) 11169.
4 S. Zhang and R. Zhang, Comput. Phys. Commun. 220, 403 (2017).
•Software to calculate anisotropic magnetostrictive coefficients.•It also calculates anisotropic magnetoelastic constants.•Evaluation of magnetocrystalline anisotropy energy.•Calculations in an automated way by Density Functional Theory calculations.•It supports the main crystal symmetries in the research field of magnetostriction.
Spin-lattice model for cubic crystals Nieves, P.; Tranchida, J.; Arapan, S. ...
Physical review. B,
03/2021, Letnik:
103, Številka:
9
Journal Article
Recenzirano
Odprti dostop
We present a methodology based on the Néel model to build a classical spin-lattice Hamiltonian for cubic crystals capable of describing magnetic properties induced by the spin-orbit coupling like ...magnetocrystalline anisotropy and anisotropic magnetostriction, as well as exchange magnetostriction. Taking advantage of the analytical solutions of the Néel model, we derive theoretical expressions for the parametrization of the exchange integrals and Néel dipole and quadrupole terms that link them to the magnetic properties of the material. This approach allows us to build accurate spin-lattice models with the desired magnetoelastic properties. We also explore a possible way to model the volume dependence of magnetic moment based on the Landau energy. This feature allows us to consider the effects of hydrostatic pressure on the saturation magnetization. We apply this method to develop a spin-lattice model for BCC Fe and FCC Ni, and we show that it accurately reproduces the experimental elastic tensor, magnetocrystalline anisotropy under pressure, anisotropic magnetostrictive coefficients, volume magnetostriction, and saturation magnetization under pressure at zero temperature. This work could constitute a step towards large-scale modeling of magnetoelastic phenomena.
Advances in theoretical and computational condensed matter physics have opened the possibility to predict and design magnetic materials for specific technological applications. In this paper, we use ...the adaptive-genetic algorithm technique for exploring the low-energy crystal structure configurations of Co 0.25 Fe 0.5 P 0.25 , aiming to find new low-energy non-cubic phases with high saturation magnetization that might be interesting for high-performance permanent magnet development.
In this paper, we perform a systematic calculation of the Fe-Ta phase diagram to discover hard magnetic phases. By using structure prediction methods based on evolutionary algorithms, we identify two ...energetically stable magnetic structures: a tetragonal Fe3Ta (space group 122) and a cubic Fe5Ta (space group 216) binary phase. The tetragonal structure is estimated to have both high saturation magnetization (μ0Ms=1.14 T) and magnetocrystalline anisotropy (K1=2.17 MJ/m3) suitable for permanent magnet applications. The high-throughput screening of magnetocrystalline anisotropy also reveals two low-energy metastable hard magnetic phases: Fe5Ta2 (space group 156) and Fe6Ta (space group 194), that may exhibit intrinsic magnetic properties comparable to SmCo5 and Nd2Fe14B, respectively.
Modern computational techniques that use a combination of electronic structure calculations, adaptive genetic algorithms, and machine learning data analysis have been recently predicting many new ...unknown structures that may exhibit desired physical properties. Yet, most of these theoretically discovered structures belong to the realm of virtual phase space, and the great challenge to experimentally observe them still remains. Based on the example of the C36 Laves phase in a Co-Fe-Ta system, we demonstrate a practical route to design and produce a material with desired properties.
In this work we develop an atomistic spin dynamics model for the ideal Mn50Al50τ-phase by means of first-principles calculations. The model is applied to study the domain wall and antiphase boundary ...phenomenology. In particular, it allows us to obtain the dependence on the interfacial exchange coupling of the nucleation and depinning fields, as well as the macroscopic magnetization profile across the antiphase boundary. We find that microscopic antiferromagnetic exchange coupling stronger than 10meV could unavoidably lead to the formation of a domain wall at the antiphase boundary.
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